


I Wish To Understand

by saturnwonder



Category: Undertale (Video Game)
Genre: Fontcest, Incest, M/M, MalexMale, Near character death
Language: English
Status: Completed
Published: 2017-07-08
Updated: 2017-07-08
Packaged: 2018-11-29 07:38:31
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,659
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11436222
Author URL: https://archiveofourown.org/users/saturnwonder/pseuds/saturnwonder
Summary: UnderFell: Sans and Papyrus have only started their relationship. Incest is frowned upon, with the price of death if found. Due to the higher status of Papyrus, their love is even further forbidden, even counted as traitorous. Along with this everyday threat, Papyrus doesn't understand why Sans won't be honest with him, causing them to fight. Can Sans save his only family and lover from dusting?





	I Wish To Understand

**Author's Note:**

> This is an entry for the contest hosted by aryisgoingaway and nagisaheichou on tumblr. Please note they are NSFW blogs!
> 
> This is also a birthday present for the wonderful babypizzawonderland on tumblr! I'm so sorry I'm late sweetie! HAPPY BIRTHDAY!!
> 
> I used a major prompt conversation as inspiration for this that was between pizza and tically, into which I hope that some of these lines were taken from the prompt and is okay! If not I will be removing this to re-edit if need be!
> 
> I hope this is okay!
> 
> Edit: Notes is the only thing edited! Fully given the a-okay from both pizza and tically. No editing on the actual story will be done.

"SANS, I SWEAR TO ASGORE IF YOU DON'T GET YOUR SHIT TOGETHER I'LL THROW YOU TO THE DOG SQUAD!"

"how about you get that stick out of your non-existing ass and back the fuck off?!"

UnderFell was such a world where you either killed or are killed, and right now Sans and Papyrus were having one of their regular screaming matches. They were outside of Snowdin's local bar, Papyrus having dragged his brother from his seat at the counter. The shorter skeleton had abandoned his post, again, and the Royal Guard second in command was already on edge due to Undyne having come for a surprise inspection only to find his brother's post empty and filthy. He loved his brother dearly, but there were times that he was at such a loss on why Sans never cared for himself or his space to the point that it was extremely infuriating to him.

He shot his gloved hand forward, grabbing the bright red collar that was wrapped around his brother's neck, before dragging him down the street and towards their shared home, Sans kicking and flailing while spouting his favorite obscurities. He unlocked the multiple locks to their home, kicked the snow off his boots, and threw the smaller body onto the couch. The door was relocked as the sound of laughter filled the room, Sans wiping a tear from his socket, "man bro, that was one hell of a performance! though, can you cut back on yanking on my collar? we don't need to breathe, but-"

"WHAT THE EVER LIVING FUCK WERE YOU THINKING?!"

Sans actually had to jump back, Papyrus unleashing a whole level of fury he hadn't seen in a long time. He was seriously pissed this time. His magic was flaring so brightly that it was painful to stare at, tears threatening to fall. "boss, bro, come on this is nothing new. i leave my post, get a drink or two at grillby's, you come knocking the door down to drag me either back to my post or home. this is nothing new," he moved forward, bringing a hand to rest on Papyrus' cheek, only to have it slapped away.

"You know very well how close Undyne is to knowing about us that if we make one false move she will have you slaughtered directly in front of me, if not after torturing me until she's bored," his volume had decreased, but his tone was sharp, fear slowly slipping in as he began to pace the room, "You are continuing to make this difficult brother, and with you loafing about as your usual self you will end up making that wrong move and I will end up loosing you! IS THAT WHAT YOU WANT SANS?!"

His bones were rattling, the tears that had lined his sockets now falling rapidly. Sans could only watch him through his own tear soaked eyes, his cheeks stained red as he got off the couch and to his little brother, his only family, and his lover. Getting close enough, he cupped Papyrus' face in his hands, happy to be allowed as the taller fell onto his knees, his face now stained a deeper reddish hue than his own.

"there... there are things in this life that i wish i could tell you. fuck, if only i could it would explain everything. i'm so sorry," he pressed their foreheads together in an attempt to console his younger brother only to be shoved silently away. Papyrus got up with no words, the sounds of leather creaking as he sadly looked down at him before turning to glide up the stairs. It felt like his soul wanted to shatter from that look.

~*~*~*~*~

Days passed after Papyrus' breakdown. He chose to avoid Sans as much as possible even to the point that he never showed to the bar to pull Sans away. Their routine was broken.

By the end of the week, Sans was losing his mind. He tried cooking, cleaning, even staying at his post with no changing results. He didn't understand why Papyrus was acting this way. Besides not being a tidy monster he could only assume that the silent treatment was due to him not being able to share why he was acting like he does. How was he able to explain that a monster, whom nobody fucking remembered but h, was responsible for not only his fast stepping through time and space but also the horrible experiments that, when said monster fell into the Core, left them alone to fend for themselves in this hell hole?

"FUCKING HELL WHAT CAN I DO?!"

He slammed his fists onto the station countertop. Multiple timelines he had tried explaining everything to him, but when the child fell and decided to reset everything was wiped clean. Papyrus remembered nothing every time. These usually happened when the child went on a genocide run, and Papyrus would... he would...

He choked out a sob. At least one thing was for certain, he was thankful that his station was far enough away from prying ears, or so he thought.

"SANS?!"

He bolted backward from his chair, crashing into the shelves behind him, magic shooting his left eye alive in rapid red flames. Bones shot up from the ground, destroying the front half of the wooden shack, forcing Papyrus to jump aside. He landed and twisted around to where his back was facing his tiny lover, his own magic now inflamed. He constructed a bone, blood red and sharp, and pointed it towards Sans.

"fucking hell, what are you doing boss?! you ignore me for a week only to finally say something but now you're-"

Papyrus cut him off, sprinting until he appeared directly in front of Sans, causing him to teleport. Before he had a chance to fully come out of it, his brother was on top of him, bone sword swung back in an attacking motion. Sans had little to no time to react as he teleported again, feeling a wave of energy from the blades impact as it hit the snowy ground.

He landed on a branch far into the woods. Screams were heard as bone after bone was launched through the forest, multiple sinking into the tree he was hiding on. Hours passed and Sans was finally able to lower his guard, having teleported multiple more times to keep from being found, as Papyrus fell forward in the snow, his energy spent and hp continuing to fall as he slowly froze from the cold.

"boss..."

~*~*~*~*~

Blankets were wrapped around the edgy skeleton, a few hot water bottles, and the portable heater they had found years ago. Since skeletons weren't all that prone to temperature it was still plausible for them to get hot or cold, so when Sans had found the piece of junk at the dump falls in Waterfall it was another pity fight as Papyrus claimed it was a useless piece of junk. Sneaking back to claim it Sans was able to find the components needed to get it working. He had kept it hidden in his closet since in such cases as this.

He paced his brother's room; Papyrus' bones weren't heating up and his hp was still steadily falling. Sweat was beading his skull as his own bones rattled in irritation since none of this made any sense. He was plenty warm and his magic was strong, yet it was like his soul was slowly collapsing on itself. There was one thing he could do, but he needed to do the unthinkable without the other's consent, "i'm sorry bro, please forgive me."

Carefully he unwrapped the body that he came to adore and love, watching his brother's ribcage fall with each un-needed breathe. He looked so beautiful as he slept: his sharpened teeth etched into a peaceful smile, the many scars, and dips carved into his bones, and the way his soul shone brightly even though it was cracked and scarred in its own way. Sans frowned seeing those marks, angry that they were there, that he was likely the cause of many if not all of them.

"it's going to be okay, boss. i know you're stronger than this. just... don't get mad."

As tenderly as he was able to, Sans reached underneath those moving ribs to grasp his goal, Papyrus' soul pulsing quicker as he got closer. His phalanges wrapped gently around it, pulling his arm out and cradling the mass of magic. It was his brother's whole self, his memories, his livelihood, his feelings: he felt all his lover's anger and pain from the last week. Papyrus felt so hurt that Sans felt he couldn't trust him enough to tell him why he felt like he needed to damn near give up when he himself was trying so hard for them both. He only desperately wanted to understand.

'activate his magic.'

"how though?!"

'activate his magic.'

"arrrrrrgh!"

"Nnngh."

Sans paused, the moan having caught him completely off guard after Boss' soul flashed brightly for a split second. His hand had brushed the bottom floating rib, one of his brother's most sensitive spots, and was rewarded with a flare of magic. Sans knew what he had to do.

"boss, i gotta do this, okay? you'll be okay, just bare with me."

He grabbed that floating rib again, stroking it harshly, enough to earn another soft moan. He continued his ministrations as his hands and mouth roamed everywhere he could reach, every spot he knew on his dear younger brother, including his soul. It dripped on Sans' tongue as he noticed the magic forming at Papyrus' pelvis, a pretty set of lips. He was doing this for him and nobody else.

"so beautiful... please let this work." Running a clawed finger up that already glistening slit Sans slid himself in, earning a sharp gasp as a reward, starting his thrusts.

~*~*~*~*~

'THIS MAKES NO SENSE. THIS FEELS WRONG. WHY IS IT SO DARK? HOW COME I CANNOT MOVE?'

Papyrus had tried moving his arms and legs to no avail. He felt so warm, yet his soul felt like it was ice. The last thing he remembered was being angry with his brother. He had startled Sans after not speaking to him for a week, only to cause him to attack out of surprise. Because of that, he attacked out of rage that left him feeling weak and he fell to his knees.

He fell! No no no he needed to get up! The Great and Terrible Papyrus couldn't leave Sans alone! His brother needed him! It was his turn to protect Sans and once again he failed by collapsing in the snow! He needed to...

"it's going to be okay, boss. i know you're stronger than this. just... don't get mad."

'SANS! SANS I'M HERE! WHAT THE HELL IS GOING ON?! ANSWER ME!'

His mind was screaming for Sans to hear him. Why wasn't he able to move or speak? This was completely insane and only angered him more as he felt shifting next to him. Something was very very wrong, and when he felt something grab at his soul he couldn't shake the numbing feeling that he could very well dust. He'd really leave Sans alone, his brother, his lover...

"how though?!" 

'HOW WHAT SANS?!'

"arrrrrrgh!"

"Nnngh."

Something brushed his bottom floating rib, and he moaned! He was able to get a reaction out to his numbskull of an older brother.

"boss, i gotta do this, okay? you'll be okay, just bare with me."

Papyrus couldn't grasp what he meant until Sans grabbed that same floating rib again, and even though he was harsher in his movements it caused Papyrus to give another moan. Sans continued to rub and caress everywhere he could reach, every spot he made Sans swear not to touch without permission, including his soul. This was still so new to them that he felt he needed to put rules up, to keep them at bay outside of their home. He felt like his soul was melting, fluids gushing forth the more Sans fingered and licked it. He could feel something like fire burning in his pelvis, causing, even more, moans to escape him. 

"so beautiful... please let this work."

His body gasped from the sudden intrusion of his pelvic region, the claw of his brother's digit running a thin scratch on the inside of his lips, pausing for only a second before it pressed past slowly and inserted in. He held off any movement for a brief moment, thrusting his finger bone easily against his blood red ecto flesh.

~*~*~*~*~

Those delicious sounds were everything Sans had dreamed about. It was taking all of his self-control to not rip the blankets off of his lover and fuck him senseless, but due to the direness of the situation, and the chance that he could very well lose him, he palmed himself through his shorts, staying as quiet as he could. The noises Papyrus was making were hot as hell and he didn't want to miss a note of the music he was playing for him and only him.

Papyrus' soul had been released, only to meet with Sans' own as it was brought forth from behind his sternum. They floated together above their bodies, away from the sweat and fluids from below, releasing their own to fall over Sans' skull. Both soul and magic were activated, yet all his brother could do was cry out pleasurably while his body was still unresponsive in movement. His hp, on the other hand, was holding, leaving Sans to try and think as he flicked Papyrus' clit with his thumb, earning a howl from the lanky skeleton.

It was all going to his cock. He could see the sheen of sweat and the dusting of a blush over his precious brother's skull, spurring him on. He didn't realize that Papyrus was moving, those stiff joints gleaming as his movements started becoming fluid, a hand reaching out to grasp at the covers as his hips jerked with splendor. Everytime Sans almost had it figured out his fingers were crushed by those warm vaginal walls making him hiss, growling in frustration, thrusting his clothed dick against the blankets. He could feel that it was working. Just a little bit more. Just a little more...

~*~*~*~*~

He had to move, he had to move, HE HAD TO MOVE!

Moaning with abandon he could feel himself reaching his peak. So close now. His arm was able to move to clutch the sheets, able to feel his soul and bones warming and rattling. He threw his ischium forward, desperately clenching to everything Sans was giving him, still not able understand his brother's reasons, just that he had to move now. Nothing else mattered but staying here with Sans. Nothing else...

"SANS!!!"

~*~*~*~*~

"papyrus!!!"

Sans rutted one last time against the bedding, his cock having slid out of his confines from how slick he was. He came hard as he felt Papyrus clamp tightly around him, their orgasms peaking together as both of their souls and genitalia gushed. Clearly exhausted, Sans crawled over Papyrus, checking his brother constantly for any further hp depletion. It had stayed where it was shortly after having started. He sighed with relief, tears running down his face.

"boss? boss, answer me, please say something."

"I love you, Sans," he turned his head to watch his reaction, "I still don't understand, and don't think I will. Just... don't think you can't tell me things."

"you're worried about that when you could have dusted? geez, you really do have a stick up your ass haha ow bro let go!"

"Damn it brother, you're insufferable!"

"heh, i love you too paps. i'm sorry. i just can't tell you, not yet."

"I'm here when you need me. With you, I'm not going anywhere."

"Are you sure, you fucking bastards?"

Undyne stood in their doorway, face twisted into a snarl.


End file.
